When I visited Edinburgh Castle, you could rent these small audio players that would narrate to you as you wandered about the grounds, explaining the history and various stories behind the specific location where you were. (Nothing sophisticated here – just a small sign in each room showing what number to punch on the audio player.)

What if, however, we could have something similar that works everywhere, all the time? You go out hiking on a trail, and listen to stories told by others who have walked that trail before.

A lot of folks have thought about the idea of a GPS-indexed ‘net. However, they tend to get bogged down in things like “the spam problem” and so on.

Podcasting provides a user experience model which fits naturally with this idea. Podcasts aren’t just a big soup of audio files, they are organized into “feeds”, each feed being (ultimately) controlled by a person and backed by their reputation (even if the feed is an aggregate of the work of multiple commentators.) Moreover, because feeds are in competition with each other for mind share, there is competitive pressure not to degrade the listening experience, which is why there aren’t very many adverts in podcasts.

Secondly, as an auditory rather than a visual experience, podcasts require less attention to be taken away from the visal experience of travelling.

A location-based podcast would, of course, have to be a lot ‘denser’ in terms of number of stories than a regular “global” cast. The GPS data serves primarily as a filter, removing entries that don’t match the users current location. This means that instead of getting an RSS feed of all of the stories, I only get the .001% of stories that happend to coincide with my current location.

The solution is a compilation cast – i.e. I select a feed based on the reputation of an editor, who combines many casts into a single aggregate feed. This combined feed will be dense enough so that at any given location, the chances of finding a matching story are good.

The thing we want to avoid is to simply grab all feeds for a given location, unfiltered. Without someone’s reputation in the loop, there’s no competition between stories, which means that the quality will rapidly degrade and spam will dominate.